A combine harvester is a machine that is used to harvest grain crops. The objective is to complete several processes, which traditionally were distinct, in one pass of the machine over a particular part of the field. Among the grain crops that may be harvested with a combine are wheat, oats, rye, barley, corn, soybeans, flax or linseed, and others. The waste (e.g., material other than grain (MOG)) discharged on the field includes the remaining dried stems and leaves of the crop which may be, for example, chopped and spread on the field as residue or baled for feed and bedding for livestock.
A combine harvester cuts crop using a wide cutting header. The cut crop is picked up and moved from outer areas of the header toward the center area of the header using an auger or belt system and conveyed to a feeder system. The cut crop is then fed by the feeding system into the threshing and separating mechanism of the combine for separating the grains from the MOG. When the MOG reaches the end of the threshing drum, it is expelled out of the rear of the combine. Meanwhile, the grain, chaff, and other small debris fall through the concaves and grates onto a cleaning device or shoe, where it is further separated from the chaff by way of a winnowing process.
Traditionally, feeder systems have included some type of feeder housing to convey crop from the header to the threshing system while providing support for the header as the combine moves through the field. In many cases, an undershot chain and slat drag (chain assembly) conveyor is employed to convey crop through the feeding system. Due to the packaging constraints of the design, however, the chain assembly is generally made-to-fit rather than being made to function optimally.
For example, conventional feeder systems distance chains in the chain assembly away from the discharge of the header auger to provide adequate clearance between moving elements (e.g. the chain) of the feeding system and the header auger. The chains are typically idled by a drum (conveyor roller) that spans the width of the housing and is supported on the ends. When the chains stretch (tension decreases) due to operational wearing, the chains are tensioned by moving the conveyor roller closer to the header auger, resulting in a smaller space between the conveyor roller closer to the header auger.
The inventors have discovered a number of shortcomings, however, with these conventional approaches. For example, each chain is tensioned the same regardless of its length relative to the others. Due to the natural wearing and elongation of the chain, the chains require regular maintenance and can easily be over tensioned. Conventional approaches address the elongation of the chain by applying a force that is generally in the direction away from the conveyor drive shaft and parallel with the chain, which causes the chain to move closer to the auger. To compensate for the wear on the chain, conventional approaches place a new chain on the conveyor roller that is located further from the header auger to prevent interference between the header auger and the chain as the chain wears and elongates. That is, conventional approaches must place a new chain further away from the header auger so more tension force can be applied as the chain elongates. As a result there is a capacity limitation with large volumes of crop as the pressure tends to relieve itself in the gap between the conveyor roller and the header auger. Further, in many cases the slats cannot be evenly spaced on the chain strand because of the concern for header to feeder clearance and accommodating the wear of the chain, imparting a cyclical load on the conveyor assembly components and reducing their operational life. What is needed is an improved feeding system.